A cyclic olefin resin is an amorphous thermoplastic olefin resin that has a cyclic olefin skeleton in its main chain and exhibits excellent performance such as good optical properties (e.g. transparency and low birefringence), low water absorbency, dimensional stability and high moisture resistance resulting therefrom and the like. Accordingly, films or sheets of cyclic olefin resins are expected to be useful for various optical applications e.g. phase difference films, polarizer protective films and light diffusion plates and for moisture-proof packaging applications e.g. medicinal product packages and food packages.
Since a film of cyclic olefin resin is low in toughness, it is known to improve the toughness of the cyclic olefin resin film by the addition and dispersion of an elastomer having hard and soft segments into the cyclic olefin resin (see, for example, Patent Literature 1).
However, the addition and dispersion of such an elastomer impairs the low refractive index of the cyclic olefin resin so that the resulting elastomer-dispersed cyclic olefin resin film shows a large in-plane retardation and would not be suitable for practical use.